In industrial control applications, various control circuits are formed in functional modules and a plurality of control modules is removably installed in a control system, to provide the system with different control functions. In order to satisfy such needs, i.e., the need of adding or removing particular module from time to time, each functional modules is provided with necessary connector modules, with a same number of electrical contacts at identical positions among all connector modules. In particular, the various functional modules form a flat cassette, with their electrical contacts formed in both sides of the flat cassettes at respectively identical positions, so that a cassette can establish electrical connections with another adjacent to either side of the other at the electrical contacts, in order to exchange signals or power.
U.S. Pat. No. 5,716,241 disclosed an “I/O Device for a Data Bus” including a connector module having such modularized connectivity. The connector module is used in a module cassette.
In order to support connections of function modules, the industry has developed a connector module. The connector module has main body in the shape of a flat cassette, with a same number of contact pins at corresponding positions in its both sides, such that one other connector module, also in the shape of a cassette, can establish electrical connections at either side of the cassette. The contact pins of a pair form a T shape, with two pins respectively extended to both sides and a third pin extended in a perpendicular direction. As a general design, the third pin includes two elastic legs configured to clip an external connector, such as one of the goldfingers provided in a circuit board. When the external connector is inserted in the third connector, the functional module in connection with the external connector establishes electrical contact with the T-shaped connector piece. That is, when no external connector is inserted, the T-shaped connector piece conducts laterally, called short circuit; when the external connector is inserted, the T-shaped connector piece additionally conducts the functional module in connection with the external connector.
WO 00/62376A1 disclosed an “Input/Output Device Having Removable Module” that has a connector module provided with such function. A T-shaped connector piece for use in the connector module is also disclosed.
US 2013/0027890 disclosed a “Connection Module Being Capable of Serving a Bus” that uses a plurality of connector modules to form a bus structure.
Changing the interconnection among contact pins by inserting a foreign object in a group of connectors was disclosed in U.S. Pat. No. 7,402,058, “Plug Connector with Short Circuit Contacts.”
In the prior art, inserting/removing either a conductive object or an insulating object to change the interconnection of a group of connectors would easily cause the sudden short or break in the circuit, during the process of insertion or removal. Such operation in turn easily cause surge or arc in the connector module or the functional module connected thereto, resulted in mail-function or even damages of the modules.
Therefore, it is necessary to provide a novel connector module that can prevent sudden short or break during operation, without the need of a complicated structure.
It is also necessary to provide a connector module that provides a plurality of connection modes and is able to prevent sudden short or break during switching of the connection modes.